Mercedes Benz E Class 350 d / 400 d Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK Mercedes Benz E Class 350 d and 400 d engine specialists. Compare prices on reconditioned, rebuilt and used OM642 V6 and OM656 straight-six diesel engines - supply & fit available nationwide.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
From £2,200 to £6,500
Used from £1,800 · Reconditioned from £2,500 · Common codes: OM642.853, OM642.873, OM656.929
From £1,800
Tested, bare/short engine
From £2,500
Rod bearings addressed, tested
From quote
Upgraded bearings, full teardown, revised valvetrain
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3 Simple Steps3 Simple Stepsto Finding the Best Mercedes Benz E Class 350 d / 400 d Replacement Engineto Finding the Best Mercedes Benz E Class 350 d / 400 d Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryMercedes Benz E Class 350 d / 400 d - Engine History & Specs at a Glance
The E 350 d and E 400 d badges represented Mercedes-Benz's flagship six-cylinder diesel offerings across the W213 E-Class generation. The E 350 d launched with the proven OM642 3.0-litre V6 diesel in 2016, before being replaced in 2018 by the E 400 d - powered by the all-new OM656 3.0-litre straight-six diesel, a more powerful and refined engine borrowed from the S-Class.
Variant HistoryMercedes Benz E Class 350 d / 400 d - Engine History & Specs at a Glance
The E 350 d and E 400 d badges represented Mercedes-Benz's flagship six-cylinder diesel offerings across the W213 E-Class generation. The E 350 d launched with the proven OM642 3.0-litre V6 diesel in 2016, before being replaced in 2018 by the E 400 d - powered by the all-new OM656 3.0-litre straight-six diesel, a more powerful and refined engine borrowed from the S-Class.
Mercedes Benz E Class 350 d / 400 d
Fuel TypeDiesel (Euro 6)
Engine Size Range3.0L (2,987 cc) - 2.9L (2,925-2,927 cc)
Power Output Range190-250 kW (258-340 hp) across the variant's historyEngine History Timeline
**2016** - W213 E 350 d launched with OM642 V6 diesel 190 kW (258 hp), 620 Nm
**2017** - Mercedes temporarily suspended E 350 d sales in Germany due to NOx emissions compliance issues
**2018** - E 400 d introduced replacing the E 350 d with the new OM656 3.0-litre straight-six diesel
**2018-2021** - E 400 d with OM656.929 producing 250 kW (340 hp) 700 Nm
**2021** - W213 facelift; E 400 d continues with revised OM656.929 now rated at 243 kW (330 hp) in some markets
**2023** - W214 generation launched; E-Class six-cylinder diesel offerings move to new engine architecture
Key Specs Snapshot
Fuel TypeDiesel (Euro 6)Engine Size Range3.0L (2,987 cc) - 2.9L (2,925-2,927 cc)Power Output Range190-250 kW (258-340 hp) across the variant's historyYears Produced2016-2023Every engine fitted to the Mercedes E Class 350 d and 400 d is covered below, with UK rebuilt pricing and known failure points.
Mercedes Benz E Class 350 d / 400 d Engine Codes - Specifications & Replacement CostMercedes Benz E Class 350 d / 400 d Engine Codes - Specifications & Replacement Cost
3.0L V6 Diesel (2016-2018)
Power Output190 kW (258 hp) at 3,400 rpmTorque620 Nm at 1,600-2,400 rpmYears Fitted2016-2018 (W213 E-Class)
Compatible Trim Levels
- E 350 d 4MATIC (W213/S213)
- E 350 d 4MATIC AMG Line
- E 350 d 4MATIC Edition
Mercedes Benz E Class 350 d / 400 d engine replacement
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£1,800-£2,800
Reconditioned
Addressed known issues, tested
£2,500-£3,800
Rebuilt
Full teardown, upgraded internals
£3,200-£4,800
Common Failure
Oil cooler seal failure - the OM642's Achilles heel. The rubber seals harden with heat cycles, causing oil to leak into the engine Vee, run down the block, and potentially mix with coolant. Turbo oil seal issues are also reported on later OM642 examples. Timing chain rattle on cold start can indicate tensioner wear.
The E Class 350 d and 400 d represent the pinnacle of Mercedes six-cylinder diesel engineering in the W213 generation. The OM642 V6 is a proven, mature design - but carries the infamous oil cooler seal failure that has plagued this engine family for years. The later OM656 straight-six is more powerful and refined, but introduces its own set of complex issues, particularly around the integrated oil/vacuum pump. Every rebuilt engine supplied through EnginesMarket includes upgraded components designed to address the original failure point, plus a minimum 12-month unlimited mileage warranty. Below, we break down what these failures cost to fix and when replacement is the smarter option.
The E 350 d V6 Weakness
Affected Vehicles
Mercedes E Class 350 d (OM642.853 / OM642.873, 2016-2018)
Typical Failure Mileage
60,000 - 100,000 miles
Root Cause
The oil cooler sits in the engine Vee and uses rubber seals that harden with heat cycles. When they fail, oil leaks into the Vee, runs down the block, and can eventually mix with coolant. The seals themselves cost as little as £5, but the labour is extensive - the intake manifold and numerous ancillaries must be removed to access them.
Why It Happens
The oil cooler sits in the engine Vee and uses rubber seals that harden with heat cycles. When they fail, oil leaks into the Vee, runs down the block, and can eventually mix with coolant. The seals themselves cost as little as £5, but the labour is extensive - the intake manifold and numerous ancillaries must be removed to access them.
Dealer (parts + labour)
£1,200-£1,800
Specialist (parts + labour)
£700-£1,100
What it involves
Removal of intake manifold, replacement of cooler seals, clean oil residue, refill fluids
Suitability
60,000-100,000 miles; effective if caught early
1 - 2 daysDealer (parts + labour)
£1,800-£2,500
Specialist (parts + labour)
£1,200-£1,800
What it involves
Seal replacement plus new turbo oil feed lines, injector seals, and intake gaskets
Suitability
100,000+ miles; addresses multiple OM642 leak points
1 - 2 daysDealer (parts + labour)
£5,500-£8,000
Specialist (parts + labour)
£3,200-£4,800
What it involves
Supply & fit of rebuilt OM642 with upgraded Viton oil cooler seals and new turbo lines
Suitability
When oil has emulsified coolant or damaged bearings
1 - 2 daysAll prices are indicative UK market ranges based on current UK specialist supplier data.| Repair Tier | Dealer (Parts + Labour) | Specialist (Parts + Labour) | What It Involves | Suitability | Estimated Time |
|---|---|---|---|---|---|
 Intermediate - Oil Cooler Seal Replacement Minor | £1,200-£1,800 | £700-£1,100 | Removal of intake manifold, replacement of cooler seals, clean oil residue, refill fluids | 60,000-100,000 miles; effective if caught early | 1 - 2 days |
 Major - Oil Cooler Seals Plus Ancillaries Best Value | £1,800-£2,500 | £1,200-£1,800 | Seal replacement plus new turbo oil feed lines, injector seals, and intake gaskets | 100,000+ miles; addresses multiple OM642 leak points | 1 - 2 days |
Full Replacement - Rebuilt Engine Best Value | £5,500-£8,000 | £3,200-£4,800 | Supply & fit of rebuilt OM642 with upgraded Viton oil cooler seals and new turbo lines | When oil has emulsified coolant or damaged bearings | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical W213 E 350 d is worth £15,000-£25,000 depending on condition and mileage. Given the high residual value, a rebuilt engine with upgraded seals and warranty is almost always justifiable if the rest of the car is sound.
Our Recommendation
Our Recommendation
If caught early with no oil-coolant emulsion, specialist seal replacement at £700-£1,100 is all you need. Once oil has blocked the turbo feed lines or emulsified coolant has damaged bearings, a rebuilt engine with upgraded seals becomes the most cost-effective long-term solution. Don't ignore oil drips under the engine bay - that's the telltale sign.
Don't Let Engine Failure Write Off Your Mercedes E Class 350 d or 400 d
Whether your E Class 350 d is suffering from oil cooler seal failure or your E 400 d is experiencing tandem pump issues or timing chain wear, EnginesMarket makes it simple to compare prices from trusted UK Mercedes specialists. Every rebuilt engine in our network includes upgraded components designed to address the original failure point - plus a minimum 12-month unlimited mileage warranty and nationwide delivery. Compare prices, choose a specialist, and get back on the road without the main dealer premium.
Compare rebuilt OM642 Mercedes E Class 350 d engine prices
12-Month Minimum
UK Specialists Vetted
Best Price GuidanceImportant Information
Important Information
"All prices are indicative UK market ranges based on historical quote data and repair requests from our network of engine specialists. Dealer pricing is estimated based on published main dealer labour rates and genuine OEM parts pricing. Specialist pricing reflects actual quote data from EnginesMarket's UK network. Actual costs vary depending on damage severity, vehicle condition, variant, and workshop location within the UK. Use our free comparison tool to get tailored quotes for your specific Mercedes E Class 350 d or 400 d. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
Mercedes E Class 350 d / 400 d Engine ReplacementFrequently Asked Questions
Question 1How much does a Mercedes E Class 400 d engine replacement cost in the UK-
Short summary: Supply-only rebuilt OM656 engines range from £4,200 to £6,500 depending on condition. With specialist fitting, budget £4,600-£7,300 total.
- OM642.853/873 (E 350 d, 258 hp, 2016-2018): rebuilt £3,200-£4,800
- OM656.929 (E 400 d, 340 hp, 2018-2023): rebuilt £4,200-£6,500
- Labour adds £400-£800 depending on specialist location
Question 2What are the signs of OM656 tandem pump failure in an E Class 400 d-
Short summary: Intermittent limp mode that clears on restart, turbo actuator issues, and P0299E6 boost pressure codes are the classic signs. In severe cases, loss of braking assistance can occur.
- Intermittent power loss or limp mode, clearing on engine restart
- P0299E6 error code (boost pressure too low)
- Juddering or clunky gear changes on longer journeys
- Oil in vacuum lines (diagnostic check required)
Question 3Is it worth replacing the engine on an E Class 350 d or 400 d-
Short summary: Yes, if the car is otherwise sound. W213 E 350 d examples command £15,000-£25,000 used, while E 400 d examples command £25,000-£40,000, making replacement viable.
- A quality rebuilt OM642 costs £3,200-£4,800 supply only
- A quality rebuilt OM656 costs £4,200-£6,500 supply only
- The OM656 is the most powerful diesel engine Mercedes ever produced for a series car
- A replacement engine with warranty costs less than the depreciation on a newer car
Question 4What causes the OM642 oil cooler seals to fail on E 350 d models-
Short summary: The rubber seals harden with heat cycles and degrade over time, causing oil to leak into the engine Vee. This is the defining weakness of the OM642 V6 engine family.
- Seal failure typically occurs between 60,000-100,000 miles
- Oil drips under the engine bay and a burning oil smell are the early warning signs
- Oil cooler seal replacement at a specialist costs £700-£1,100
- Later OM642 engines (2014+) have improved seals but can still fail
Question 5What is the difference between the OM642 and OM656 engines in the E Class-
Short summary: The OM642 is a 3.0-litre V6 diesel (2016-2018 E 350 d); the OM656 is a 3.0-litre straight-six diesel (2018-2023 E 400 d) - more powerful, more refined, and borrowed from the S-Class.
- OM642: V6 configuration, 258 hp, 620 Nm - proven but has oil cooler seal issues
- OM656: straight-six configuration, 340 hp, 700 Nm - smoother, more powerful, but has tandem pump issues
- The OM656 replaced the OM642 in the E-Class from 2018 onwards
- Both are Euro 6 compliant with AdBlue emissions treatment
Question 6How long does a Mercedes E Class 400 d engine last-
Short summary: With proper maintenance and 8,000-10,000 mile oil changes, OM656 engines regularly reach 200,000+ miles. Some examples have exceeded 100,000 miles with proper servicing.
- OM656 straight-six is a modern, efficient design with robust bottom end
- Tandem pump replacement at 40k-80k miles is a known requirement for early examples
- Camshaft and rocker inspection at 80k-100k miles is recommended
- Short oil change intervals (8k miles) are critical for longevity
Why Choose UsCompare Mercedes E Class 350 / 400 dEngine PricesToday
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12-Month Warranty on every rebuilt OM642 / OM656 engine
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